In conventional centerless grinding as is well-known in the art, a grinder has a grinding wheel and a regulating wheel, oppositely disposed to a work support, located therebetween. The work support carries a workpiece of revolution which is contacted by the respective grinding and regulating wheels. To achieve a "rounding up" action, the work is elevated to such point that its centerline lies above a line of center between the respective regulating and grinding wheels. Thus, a "rounding-up" triangle is established, having a base equal to the line of centers between the two wheels and sides manner to obtain a slight axial feed component for propelling the workpiece toward a positive stop and thrusting the shoulder surface to be ground against the side of the grinding wheel. Difficulties are encountered by grinding with the side of the wheel: rapid deterioration of the side face of the grinding wheel may occur, and a sometimes undesirable "cross-hatching" finish appears on the shoulder as a prior ground surface passes the grinding wheel at a different attitude. To obtain flatness control of the grinding face and to relieve built-up pressures, the wheel is often relieved on the side leaving only a rim of work contacting surface to do the job, and wheel breakdown is accelerated. It has been suggested that a conventional centerless grinder be configured to have frusto-conical surfaces formed on a grinding wheel, wherein the grinding wheel spindle would be canted to the axis of a workpiece and fed along a vector aimed at the juncture of the work diameter and shoulder, as is often done on center type grinders known as "angular wheelslide plunge grinders". One of the most important advantages of angular feed grinding lies in the possibility of reconditioning the wheel profile automatically while maintaining the apex of the profile in the same relationship with the junction of the ground surfaces. In the angular plunge grinder art, however, when viewing the part axially, i.e., in circular cross-section, the wheel faces appear elliptical and have their minor axes coincident with the line of contact of the frusto-conical surface of the wheel along the part.
If a conventional centerless grinder would be fitted with a frusto-conical grinding wheel, and the grinding wheel be swiveled with sides parallel to a juncture-aimed feed vector so as to present a frusto-conical surface parallel to the regulating wheel cylinder and workpiece, it may be seen that, as the workpiece is positioned above the line of centers of the wheels (by necessity), the workpiece would contact the parallel cylinder of the regulating wheel along a line of contact but would contact the grinding wheel only at one end of the wheel, since the minor axes of the ellipses formed by the foreshortened view of the sides of the wheel would be coincident only on the line of centers of the wheels. Therefore, it is seen that the workpiece must be laid along the frusto-conical surface of the grinding wheel such that their axes fall on the same plane. To accomplish this contact with the grinding wheel, a special, articulatable work support fixture would somehow have to be arranged to tilt the workpiece along the frusto-conical face, and the regulating wheel would have to be tilted accordingly around the pivot of the regulating wheel housing in order to contact the workpiece. However, it may now be seen that as the grinding wheel diminishes in diameter due to wear and dressing, and is fed in conventional manner along the line of centers of the wheels, that the workpiece would have to be readapted after a certain amount of wheel wear to a new cone which now comprises the wheel. To date, no such conical wheel work support adapter has been known for a conventional centerless grinder having feed and compensating movements of the wheels along a line of centers between the wheels, with the workpiece being positioned off the line of centers between the wheels.
Applicant has obviated the difficulties inherent in the prior art devices by an angular feed centerless grinder design which readily applies a frusto-conical wheel to a cylindrical workpiece, feeding the regulating wheel and grinding wheel directly toward the workpiece, keeping a constant angle between the feed vectors. Further, a diminished grinding wheel cone will not affect the geometric quality of the workpiece, in that a conical surface is continually presented to contact the finished workpiece along a substantially constant line of contact. A shoulder on a workpiece is further ground to a high degree of flatness by a frusto-conical surface on the grinding wheel, since the frusto-conical surface contacts the shoulder along a substantially constant radial line of contact.
It is therefore an object of the present invention to provide an angular feed centerless grinder having certain substantially constant grind parameters throughout the life of the grinding wheel and the regulating wheel.
It is a further object of the present invention is to provide an angular feed centerless grinder capable of ease of setup about a substantially constant work centerline for a variety of workpiece sizes.